Wooden laminated floor product to improve strength, water protection and fatigue resistance

ABSTRACT

A vehicular surface floor has a length and a width, made from a plurality of planks. Each plank has a length substantially equal to the length of the floor and a width that is less than the width of the floor. Each plank has first and second side surfaces and are arranged side by side so that a first side surface of one plank faces a second side surface of an adjacent plank, a joint region being formed at an area where the first side surface meets the second side surface. Each plank consists of at least two rows of boards, and each board consists of a plurality of segments joined end-to-end to one another by shaped coupling portions and side by side along a glue line; so that each of the at least two rows are longitudinally offset from an adjacent row, and a glue line of one row is offset from a glue line from an adjacent row.

FIELD OF THE INVENTION

The present invention relates to laminated product to improve thestrength, water protection and the fatigue resistance on a laminatedwooden cargo-carrying floor of a cargo-carrying body.

BACKGROUND OF THE INVENTION

Conventional wood flooring for over-the-road truck trailers andcontainers is normally manufactured with hardwoods such as oak, maple,birch, beech, etc. The green lumber used as a starting material in suchmanufacture is suitably dried in special drying chambers undercontrolled conditions. The dried lumber is then sawed into strips ofrectangular cross-section and defective portions are eliminated by crosscutting the strips. After, with a double end matching or during thecross cutting process, hooks or knuckle-type joints are formed at theends of the lumber strips. The joints are a simple mechanical couplingbetween the ends of opposing lumber strips without significant adhesivebonding at the joint itself. The relatively defect-free lumber stripsare coated on their vertical sides or edges with an adhesive such asurea-melamine formaldehyde or polyvinyl acetate. The minimum length ofthe lumber strips is 12 inches, as requested by industry standard, and amaximum length of 6 to 7 feet, which is limited by the width of thedouble end matcher equipment which makes the desired profile of thejoint. The uncured edge-glue lumber strips are then assembled by hand ona conveyor by placing them side-by-side and one in front of otherstrips, which were previously assembled.

The manual assembly of the strips is a very important element and isessential to reach the desired mechanical properties of the floor andmeet industrial requirements. In fact, the persons that assemble thestrips must:

-   -   1) minimise the number of joints by square foot; and    -   2) maximise the space between joints in a way that it is        equalised all over the wood surface.

These two elements maximise the floor's mechanical support and itsdurability. The length of the lumber strips has an effect on the numberof joint par square foot and the space between the joint. Applying heatand edge pressure to large sections of the assembled lumber strip in apress cures the adhesive thus forming a unitary panel.

At the output of the press, the cured laminated wood is cut to a desiredlength (up to about 60 feet) and width (about 6 to 18 inches) to formboards. The boards are then planed to a desired thickness and shiplapsand crusher beads are machined on the sides, such as shown in FIG. 1. Ashiplap is a rectangular projecting ledge along the length on each sideof a floorboard. A crusher bead is a small semi-circular projectionrunning along the length on each side of a board and placed over orbelow a lip.

When the floorboards are assembled in a trailer such that the side edgesof corresponding boards are squeezed together, the shiplaps of adjacentboards overlap to form a seam. The crusher beads provide spacing betweenadjacent boards and help in preventing buckling of the boards due toexpansion of the board following absorption of water. Wood putty isapplied at the joints on the top and bottom surfaces of the boards tofill any gaps.

Finally, the underside of the floorboards is coated with a polymericsubstance termed as “undercoating” to provide moisture protection. Thefinished floorboards are assembled into a kit of about eight boards forinstallation in a trailer.

Normally, a kit consists of two boards with special shiplaps so thatthey will fit along the road and curb sides of a trailer. The otherboards may be identical in design and they are placed between the roadand curb sideboards. In some trailers, a metallic component such as ahat-channel may be placed between any two adjacent boards. The metalliccomponent becomes part of the floor area. The boards adjacent thehat-channel have machined edges designed to mate with the flanges of themetallic component. All the boards are supported by thin-walledcross-members of I, C or hat sections, each having an upper flange orsurface, which span the width of the trailer and are spaced along thelength of the trailer. Each floorboard is secured to the cross-membersby screws or other appropriate fasteners extending through the thicknessof the board and the upper flanges of the cross-members.

Hardwood-based laminated wood flooring is popularly used in trucktrailers since it offers many advantages. The surface characteristics ofhardwoods such as high wear resistance and slip resistance are mostdesirable. The strength and stiffness of the flooring is important forefficient and safe transfer of the applied loads to the cross-members ofthe trailer. The shock resistance of wood is useful to withstand anysudden dropping of heavy cargo on the floor. Nail holding capability andthe ability to absorb small amounts of water, oil or grease withoutsignificantly affecting slip resistance are yet additional favourableproperties of hardwood flooring.

Although conventional wood flooring has many desirable features, it alsosuffers from certain disadvantages. One of the main problems is theeffect of the end of each lumber strips on the strength and durabilityof the floor.

It is well known in the flooring industry that the joint between two endlumber strips is the structural weakness point of a laminated floor fortwo reasons.

First, the joint reduces the capacity of the floor to react properly tothe dynamic action of a moving lift truck placing or removing heavycargo into the trailer. A lift truck is often used on the trailer floorto load and unload cargo. A large amount of the weight of the lift truckand the cargo is transferred to the floor through the wheels of thefront axle of the lift truck due to the momentary raising of the rearaxle when the lift truck is dynamically placing or removing heavy cargoon the floor. The dynamic action of a moving lift truck placing heavycargo on the trailer floor places a severe stress concentration on thefloor and some of the cross-members. Bending of the floor between twoadjacent cross-members due to any applied load on the top of the floorhas a tendency to open the hook joints and enlarge the gaps. The effectof repeated lift truck operations on the conventional wood floor causesconsiderable fatigue damage including: de-lamination of the edge gluedlumber strips near the joints leading to the “pop-out” of the lumberstrips on the underside; crack initiation and propagation in the woodstrips on the underside of the floor due to tensile stresses; andcracking of edge glue lines due to shearing, transverse bending andtwisting of the floor.

Second, the joint represents a weak area of protection against watercoming from the road. Capillarity and the tendency of the end grain ofwood to absorb and store water over time eventually creates a problem ofwater leaks into the trailer and a degradation of the structuralintegrity surrounding the joint area. Also, because of the way thatconventional floors are made, when de-laminating occurs, the cracks willpenetrate through the laminated floor creating a weak area where thewater can enter. The combination of moisture attack and fatigue damageto the wood floor affects its performances thus necessitating its repairor replacement. In some cases, catastrophic structural failure of thetrailer floor system may occur leading to the unacceptable injury toworking personnel and damage to machinery.

In the past decade, and still today, the research and developmentefforts to improve the disadvantages of conventional floors are mainlyfocused on the use of new materials such as plastic, fiberglass, etc.,and on the interaction with wood to create new composite floors.

The idea of using plastic, steel, fiber carbon, kevlar, fiberglass andother material to reinforce wooden structure is not new and has beenstudied by many. More recently, Padmanabhan U.S. Pat. No. 5,928,735 andTunis U.S. Pat. No. 6,601,357 propose solutions in the specific field oflaminated trailer floor.

Padmanabhan applies a reinforced thermoplastic ply to the entire bottomof the floor. Because reinforced ply increases the strength andstiffness of the trailer floor, the hardwood portion of the floor can bethinner. The result is a stronger and lighter trailer floor. Thereinforced ply also provides a water impervious layer protecting theentire bottom part of the floor from moisture coming from the road.

Tunis provides a solution for moisture protection only. Thethermoplastic ply is not reinforced and has as its sole purpose theprotection of the floor from the attack of water spray and moisture overtime. The thermoplastic ply covers the entire bottom surface of thefloor.

Others have taken a different approach and have proposed solutionsimproving some aspect of the laminated wood floor without adding anycomposite material, but by improving the manufacturing method ortechnique. In U.S. Pat. No. 6,843,877 (Risi) and in U.S. Pat. No.6,957,675 (Risi) there is proposed a new machine and manufacturingmethod which uses a finger joint type end stick design to improve thedurability and the moisture resistance of the laminated floor. Thepresent invention takes that the same avenue creating innovativesolutions where an improvement of the strength can be achieved withoutusing composite materials but only by using more efficiently the actualtechniques of manufacturing and the characteristics of the raw materialitself.

SUMMARY OF THE INVENTION

The present invention is a new product to improve the strength, fatigueresistance and provide moisture resistance on a laminated woodencargo-carrying floor of a cargo-carrying body such as that of either atransport vehicle or a transport container, which offer an intermediatesolution to a composite floor but at a much lower cost.

In accordance with one aspect of the present invention, there isprovided a vehicular surface floor having a longitudinal length and alateral width, said vehicular surface floor comprising:

a) a plurality of wood planks extending longitudinally up to a lengthsubstantially equal to the longitudinal length of said floor, each plankhaving a top surface, a bottom surface opposite said top surface, and afirst and second side surfaces extending between said top surface andsaid bottom surface, where said plank has a width that is less than thelateral width of said floor, said floor being formed of said pluralityof planks arranged side by side, each plank being formed of at least tworows of a plurality of boards, each board being formed of a plurality ofsegments joined end-to-end to one another by shaped coupling portionsand side by side along a glue line, each of said at least two rows beinglongitudinally offset from an adjacent row, so that a glue line of onerow is offset from a glue line from an adjacent row; and

b) said plurality of planks being arranged side by side such that atleast one of said first and said second side surfaces of each of saidplanks faces one of said second or first side surfaces of adjacentplanks to form the floor, a joint region being formed at locations atwhich said first side surface faces said second side surface of adjacentplanks.

In accordance with another aspect of the present invention, there isprovided a vehicular surface floor having a longitudinal length and alateral width, said floor comprising:

-   -   a plurality of planks, each plank having a length substantially        equal to said length of said floor and a width that is less than        said width of said floor, each plank having first and second        side surface, said planks being arranged side by side so that a        first side surface of one plank faces a second side surface of        an adjacent plank, a joint region being formed at an area where        said first side surface meets said second side surface, wherein:    -   each plank consists of at least two rows of boards;    -   each board consists of a plurality of segments joined end-to-end        to one another by shaped coupling portions and side by side        along a glue line;        -   each of said at least two rows are longitudinally offset            from an adjacent row, so that a glue line of one row is            offset from a glue line from an adjacent row.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood after reading adescription of a preferred embodiment thereof made in reference to thefollowing drawings in which:

FIG. 1 is a perspective cross section of a conventional wood flooraccording to the prior art;

FIG. 2 is a perspective cross section of a conventional wood flooraccording to a preferred embodiment of the invention; and

FIG. 3 is a perspective view of a floor, including an undercoat layer.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Referring now to FIG. 2, there is shown a perspective cross-section of awood plank 1. A plurality of such wood planks 1 are arranged side byside to form a floor 10.

Each wood plank 1 is made of at least two layers of boards 100. Eachboard is made of a plurality of strips 101, each strip being joinedend-to-end at a joint region 103, and each set of strips being joinedside by side along a glue line 105.

In a preferred embodiment of the invention, the strips are hardwoodboards, and the hardwood is further preferably selected from the groupconsisting of oak, maple, birch, beach, and larch.

In accordance with a preferred embodiment of the invention, one layer100 is longitudinally offset from another layer 100, such that the gluelines of one board are offset from the glue lines of another board, asshown in FIG. 2. Although only two layers are shown in FIG. 2, it willbe understood that more layers can be used depending on the thickness ofthe strips, and on the desired overall thickness of the floor 10.

In the case of FIG. 2, the offsetting of one layer with respect toanother automatically creates the shiplap joint, leaving only thecrusher bead to be made.

It will further be appreciated that the plank of FIG. 2 can be made asin the prior art, that is a full thickness plank, which is then split intwo and glued together, but offset, along glue line 106. Furthermore,one of the two halves is rotated front to back (180°), so that joints donot face each other. Also, if more than one layer is used, for examplethree, then instead of a shiplap joint, a tongue-and-groove system canbe used.

Furthermore, the butt end joints of the sticks of the bottom layer donot face completely the butt end joints of the sticks of the upper partof the floor.

As is the case of convention floors, the floor of the present inventioncan be further provided with an undercoating. The undercoating can be anunreinforced polymer, a paint or a fiber-reinforced polymer. Theundercoating further can cover substantially 100 percent of said bottomsurface or less (for example at areas where it is more important), andpartially or substantially cover both side surfaces of said floor.

It should be pointed out that the lamination of the top to the bottompart of the floor can be also done for other wooden floors, such asthose used in the flat bed industry. Those wooden floors are typicallynot laminated and are made with solid wooden planks of 8 inches wide by8 to 12 feet long, with different thicknesses (usually 1 ¼ or 1 ½ inchesthick). After the board is planed, the plank has a ship lap in bothsides, as in conventional laminated floor, with a final thickness of 1 ⅛or 1 5/16 (1 ⅜).

The new product according to the present invention offers manyadvantages as follows:

It reduces the quantity of the raw material needed to produce the samesquare footage; usually, conventional floors are made with 14 stickswhereas the new product is made with only 13 sticks.

Depending on the way the new product is produced, it may increase theproductivity of manufacturing;

There is no way for the water to go through the floor because there areno glue lines or butt end joints which go straight from the bottom tothe top;

Because of the way it is designed, even if de-lamination does occurbetween sticks on one of the layers, it will be difficult for the waterto go through the floor;

Because there are no joints going straight through the floor, thenegative effect of the conventional joint is decreased, which in turnincreases the fatigue resistance when the laminated floor is understress during the forklift passages on the floor.

The product according to the present invention has better durabilitycharacteristics over the traditional laminated wooden floor used in theindustry and also offers a more economic alternative to composite floorsusing reinforced ply like fibreglass, which are very expensive.

Although the present invention has been explained hereinabove by way ofa preferred embodiment thereof, it should be pointed out that anymodifications to this preferred embodiment within the scope of theappended claims is not deemed to alter or change the nature and scope ofthe present invention.

1. A vehicular surface floor having a longitudinal length and a lateralwidth, said vehicular surface floor comprising: a) a plurality of woodplanks extending longitudinally up to a length substantially equal tothe longitudinal length of said floor, each plank having a top surface,a bottom surface opposite said top surface, and a first and second sidesurfaces extending between said top surface and said bottom surface,where said plank has a width that is less than the lateral width of saidfloor, said floor being formed of said plurality of planks arranged sideby side, each plank being formed of at least two rows of a plurality ofboards, each board being formed of a plurality of segments joinedend-to-end to one another by shaped coupling portions and side by sidealong a glue line, each of said at least two rows being longitudinallyoffset from an adjacent row, so that a glue line of one row is offsetfrom a glue line from an adjacent row; and b) said plurality of planksbeing arranged side by side such that at least one of said first andsaid second side surfaces of each of said planks faces one of saidsecond or first side surfaces of adjacent planks to form the floor, ajoint region being formed at locations at which said first side surfacefaces said second side surface of adjacent planks.
 2. A vehicularsurface floor according to claim 1, wherein said plurality of woodboards are hardwood boards.
 3. A vehicular surface floor according toclaim 2, wherein said hardwood is selected from the group consisting ofoak, maple, birch, beach, and larch.
 4. A vehicular surface flooraccording to claim 1, wherein said floor is further provided with anundercoating.
 5. A vehicular surface floor according to claim 4, whereinsaid undercoating is an unreinforced polymer, a paint or afiber-reinforced polymer.
 6. A vehicular surface floor according toclaim 1, wherein said undercoating covers both substantially 100 percentof said bottom surface, and partially or substantially covers both sidesurfaces of said floor.
 7. A vehicular surface floor according to claim1 wherein said first side surface is provided with an upper lip portion,said second side surface is provided with a lower lip portion, and saidfirst side surface of one of said planks which faces said second sidesurface of an adjacent plank forms a ship lap joint in which said upperlip portion at least partially overlies said lower lip portion.
 8. Avehicular surface floor according to claim 7, wherein each of saidplanks consist of only two rows of boards, and said ship lap joint isautomatically formed by offsetting a first row of boards from a secondadjacent row of boards.
 9. A vehicular surface floor having alongitudinal length and a lateral width, said floor comprising: aplurality of planks, each plank having a length substantially equal tosaid length of said floor and a width that is less than said width ofsaid floor, each plank having first and second side surface, said planksbeing arranged side by side so that a first side surface of one plankfaces a second side surface of an adjacent plank, a joint region beingformed at an area where said first side surface meets said second sidesurface, wherein: each plank consists of at least two rows of boards;each board consists of a plurality of segments joined end-to-end to oneanother by shaped coupling portions and side by side along a glue line;each of said at least two rows are longitudinally offset from anadjacent row, so that a glue line of one row is offset from a glue linefrom an adjacent row.
 10. A vehicular surface floor according to claim9, wherein said plurality of wood boards are hardwood boards.
 11. Avehicular surface floor according to claim 10, wherein said hardwood isselected from the group consisting of oak, maple, birch, beach, andlarch.
 12. A vehicular surface floor according to claim 9, wherein saidfloor is further provided with an undercoating.
 13. A vehicular surfacefloor according to claim 12, wherein said undercoating is anunreinforced polymer, a paint or a fiber-reinforced polymer.
 14. Avehicular surface floor according to claim 9, wherein said undercoatingcovers both substantially 100 percent of said bottom surface, andpartially or substantially covers both side surfaces of said floor. 15.A vehicular surface floor according to claim 9, wherein said first sidesurface is provided with an upper lip portion, said second side surfaceis provided with a lower lip portion, and said first side surface of oneof said planks which faces said second side surface of an adjacent plankforms a ship lap joint in which said upper lip portion at leastpartially overlies said lower lip portion.
 16. A vehicular surface flooraccording to claim 15, wherein each of said planks consist of only tworows of boards, and said ship lap joint is automatically formed byoffsetting a first row of boards from a second adjacent row of boards.